BAGRAM AIR FIELD, Afghanistan — The first troops to leave Afghanistan as part of the U.S. drawdown handed over their slice of battlefield Wednesday to a unit less than half their size and started packing for home.

When the 650 members of the Iowa National Guard’s 1st Squadron, 113th Cavalry Regiment arrived in Afghanistan in November 2010, bases didn’t have enough housing, translators were in short supply and chow halls were packed. Commanders were using a buildup of 33,000 extra troops for a major push that they said would turn the tide of the war against the Taliban insurgency.

Nine months later, it’s still unclear if that push has succeeded, but the pullback has begun. Although major combat units are not expected to start leaving until late fall, two National Guard regiments comprising about 1,000 soldiers in all are withdrawing this month.

U.S. President Barack Obama announced last month that he would pull 10,000 of the extra troops out in 2011 and the remaining 23,000 by the summer of 2012.

Three hundred soldiers will take over from the 650 departing troops.

The commander of the outgoing unit said he expects his successors will be able to build on their accomplishments.

Lt. Col. David Updegraff said he felt he could have completed his mission with a smaller force, but that the extra numbers made it significantly easier.

Some in the 113th said 650 soldiers were barely enough.

“Most of our platoons were short-manned quite often. We were running with the minimum amount that we safely can. And they were running long missions, long days,” said Staff Sgt. Brian Pals, 34, of Hartley, Iowa.

They had to spend extra time demonstrating techniques to Afghan police officers who were illiterate and had to teach Afghan soldiers basic map-reading skills, said Staff Sgt. Doug Stanger, 42, of Urbandale, Iowa.

“It takes a lot more of us to mentor them,” Stanger said. Although commanders have said their mission in Afghanistan has not changed, manpower-intensive activities such as these are likely to lessen with smaller forces. The current push appears to be for more quick-strike missions that eliminate insurgent leaders while the Afghan security forces are left to keep the peace.

And while the Afghan army and police have improved drastically, there’s still a long way to go.

“You’ve got to pull teeth to get the ANP [Afghan National Police] to do anything,” said Pfc. Scott Silverblatt, 22, of McHenry, Illinois.

As the soldiers go back, they all say they’re prepared for the same question: Should we be over there? Pals says yes, because the training is helping. Stanger also says yes, because most Afghans really want the help. Silverblatt agrees, because a too-quick departure could throw the Afghan economy built up around bases such as Bagram into a tailspin.

“If we leave, we’ve just messed up the whole country all over again,” Silverblatt said.

A fourth soldier — Staff Sgt. Jesse Ross of Des Moines — said he isn’t sure, given the strong words coming from Afghan President Hamid Karzai, about how Americans risk becoming occupiers.